Packaging the 3 billion nucleotides of the human genome into the nucleus of a cell requires tremendous compaction. To accomplish this feat, DNA in our chromosomes is wrapped around spools of proteins called histones to form dense repeating protein/DNA polymers known as chromatin. Far from serving as mere packaging modules, chromatin templates form the basis of a newly appreciated and fundamentally important set of gene control mechanisms termed epigenetic regulation. By conferring a wide range of specific chemical modifications to histones and DNA, epigenetic regulators modulate the structure, function, and accessibility of our genome, thereby exerting a tremendous impact on gene expression. Hundreds of epigenetic effectors have recently been identified, many of which are chromatin-binding or chromatin-modifying enzymes. Significantly, an increasing number of these enzymes have been associated with a variety of disorders such as cancer. Thus, therapeutic agents directed against this emerging class of gene regulatory enzymes promise new approaches to the treatment of human diseases.
Additionally, the relatively rapid acquisition of resistance to cancer drugs remains a key obstacle to successful cancer therapy. Substantial efforts to elucidate the molecular basis for such drug resistance have revealed a variety of mechanisms, including drug efflux, acquisition of drug binding-deficient mutants of the target, engagement of alternative survival pathways and epigenetic alterations. Rare, stochastic, resistance-conferring genetic alterations have been found within a tumor cell population selected during drug treatment. See Sharma et al., Cell 141(1):69-80 (2010). The KDM5/JARID1 family of histone demethylases was found to play a role in cancer resistance. The KDM5/JARID1 family of demethylases in humans contains four members, KDM5A, KDM5B, KDM5C and KDM5D. KDM5 family members contain five conserved domains: JmjN, ARID, JmjC, PHD and a C5HC2 zinc finger. Amino acid sequences of KDM5A, KDM5B, KDM5C and KDM5D are known and are publicly available, e.g., see UniProtKB/Swiss-Prot (see e.g., KDM5A (e.g., P29375-1 and P29375-2), KDM5B (e.g., Q9UGL1-1 and Q9UGL1-2), KDM5C (e.g., P41229-1, P41229-2, P41229-3 and P41229-4) and KDM5D (e.g., Q9BY66-1, Q9BY66-2 and Q9BY66-3). There is currently a need for compounds that inhibit of KDM5 demethylases for treating hyperproliferative diseases, preventing drug resistance, and/or for improving the efficacy of other cancer treatments (e.g. targeted therapies, chemotherapies, and radiotherapies.